Abstract #3319

The impact of multi-compartment microstructure on single-compartment T1 estimates

Giorgia Milotta¹, Nadège Corbin^1,2, Antoine Lutti³, Siawoosh Mohammadi^4,5, and Martina Callaghan¹

¹Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, ²Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS/University Bordeaux, Bordeaux, France, ³Laboratory for Research in Neuroimaging, Department for Clinical Neuroscience, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, ⁴Department of Systems Neurosciences, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, ⁵Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

Quantitative relaxometry in the brain is appealing because of its microstructural sensitivity. Estimating bulk parameters assumes a single relaxation time per voxel, which is only valid when the residency time is short with respect to T₁. In reality, the relative contribution of sub-compartments will depend on flip angle and echo time. Here, we simulate a two-compartment model (myelin and intra-extracellular water) and estimate T₁ with FA-specific signals derived via three estimation schemes. We quantify the impact of myelin water fraction, residency time and transmit field inhomogeneity on these estimates and find good correspondence with in vivo T₁ estimates at 7T.

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